U.S. Frost Dates by Weather Station

NOAA station USW00094823 · Pennsylvania

Frost Dates for Pittsburgh, PA

NOAA weather station Pittsburgh International Airport (USW00094823), Pennsylvania · elevation 1203 ft (367 m) · hardiness zone 6b*

  • Lower-risk planting dateafter May 12only 1 spring in 10 still has a frost later
  • Typical last frostApril 2350% chance of a frost after it
  • Typical first fall frostOctober 2350% chance of a frost before it
  • Frost-free season181 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Pittsburgh, PASpring: a frost after April 9 in 9 years out of 10, after April 23 in half of the years, after May 12 in 1 year out of 10. Fall: the first frost comes before October 9 in 1 year out of 10, before October 23 in half of the years, before November 6 in 9 years out of 10. Typical frost-free season: 181 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 23First frost ~Oct 23Frost season at Pittsburgh, PASpring: a frost after April 9 in 9 years out of 10, after April 23 in half of the years, after May 12 in 1 year out of 10. Fall: the first frost comes before October 9 in 1 year out of 10, before October 23 in half of the years, before November 6 in 9 years out of 10. Typical frost-free season: 181 days.JFMAMJJASONDLast frost ~Apr 23First frost ~Oct 23
frost likely chance fading 90% → 10% frost-free in a typical yearThe year at a glance. Blue: frost is likely; the gradient fades as the chance drops from 90% to 10%; green: the frost-free part of a typical year.

Frost dates (32°F)

Probability of frost, based on 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 12October 9
50% (typical)April 23October 23
90% (likely)April 9November 6
Frost-free season (32°F, 50% chance)
181 days
Hard frost (28°F), last in spring, 50% chance after
April 12
Hard frost (28°F), first in fall, 50% chance before
November 4

The last 15 years (2006–2020 normals)

Typical last frost April 21 (2 days earlier than the 30-year normal), typical first fall frost October 26 (3 days later). Frost-free season 186 days.

A shorter, more recent NOAA period. The 30-year normals above remain the main reference: 15 years carry more year-to-year noise.

Add these dates to your calendar Yearly reminders for the typical last frost, the lower-risk planting date and the typical first fall frost (.ics).

How the chance of frost changes with the date

Spring at Pittsburgh: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 12, 20% May 5, 30% May 1, 40% April 27, 50% April 23, 60% April 21, 70% April 18, 80% April 15, 90% April 9. Observed last spring frost in recent years: 2021 May 1, 2022 April 29, 2023 April 25, 2024 April 7, 2025 April 17, 2026 May 2.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 12Apr 23Apr 92021: May 12022: April 292023: April 252024: April 72025: April 172026: May 2Fall at Pittsburgh: chance of a frost before this dateFall, chance of a frost before the date: 10% October 9, 20% October 14, 30% October 18, 40% October 21, 50% October 23, 60% October 26, 70% October 29, 80% November 1, 90% November 6. Observed first fall frost in recent years: 2021 November 3, 2022 October 29, 2023 November 1, 2024 October 27, 2025 October 26.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 9Oct 23Nov 62021: November 32022: October 292023: November 12024: October 272025: October 26
Two charts, because spring and fall answer different questions: in spring, the chance that a frost still comes after a date; in fall, the chance that the first frost has already come before it. NOAA publishes these odds from 10% to 90%, so the lines stop there. ◆ marks the actual date in each recent year.

What actually happened in recent years

Observed dates of the last spring and first fall frost (32°F) at this station; ◆ marks them on the charts above
YearLast spring frostFirst fall frost
2021May 1November 3
2022April 29October 29
2023April 25November 1
2024April 7October 27
2025April 17October 26
2026May 2season not over yet

What these dates mean

The 181 days between the 50% dates of April 23 and October 23 in Pittsburgh frame the interval in which most garden work can be arranged. On April 23 there is a 50% chance of a frost later than this date, and on October 23 there is a 50% chance of a frost earlier than this date, giving gardeners an even-odds point for planning.

For tender crops the cautious spring date is May 12, which carries a 10% chance that a frost will occur later, while the early-season gamble is April 9 with a 90% chance of a later frost. In the fall the cautious date to finish harvesting tender crops is October 9, also a 10% chance of an earlier frost, and the late-season gamble is November 6 with a 90% chance of an earlier frost. The median hard-frost dates are April 12 in spring and November 4 in fall.

A hard frost at 28 °F is more damaging than a light frost at 32 °F because it can freeze plant tissue that would survive a light frost.

How to read the probabilities

The dates are probabilities from 30 years of weather, not a forecast for this year.

  • Spring: "10% after May 12" means that in about one spring out of ten a frost still happens after that date. The 90% date is the earliest: a frost after it happens in most years.
  • Fall: "10% before October 9" means that in about one fall out of ten the first frost arrives before that date.
  • 50% is the typical date: half of the years are earlier, half are later.
  • A light frost (32°F) damages tender plants; a hard frost (28°F) also stops most hardy vegetables.

Nearby weather stations

Map of weather stations near Pittsburgh, PANumbered nearest stations: 1 — near Industry, PA — 14 mi; 2 — McKeesport, PA — 21 mi; 3 — Steubenville, OH — 23 mi; 4 — Butler, PA — 29 mi; 5 — near Wheeling, WV — 35 mi.PAOHWV25 mi · 40 km1. near Industry, PA — 14 mi12. McKeesport, PA — 21 mi23. Steubenville, OH — 23 mi34. Butler, PA — 29 mi45. near Wheeling, WV — 35 mi5
  1. near Industry, PA 14 mi (23 km)
  2. McKeesport, PA 21 mi (34 km)
  3. Steubenville, OH 23 mi (37 km)
  4. Butler, PA 29 mi (47 km)
  5. near Wheeling, WV 35 mi (56 km)

Sources

* Hardiness zone 6b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 40.4847, -80.2144.